JP6801186B2 - Projector and control method - Google Patents

Description

The present invention relates to a technique for controlling the rotation angle of a retardation plate in a projector.

A light source device using a solid-state light source such as a laser diode is known. In such a light source device, light in a certain wavelength band output from a solid-state light source is separated by a polarization separation mirror. One of the separated lights is guided to the phosphor as excitation light, and the phosphor emits light in a wavelength band different from that of the solid-state light source. The light output from the phosphor is combined with the other separated light and output as light containing more wavelength band components.

Such a light source device has a problem that the white balance of the output light is deviated due to a change in the characteristics of a solid light source or a phosphor with time. On the other hand, for example, Patent Document 1 describes a light source device that compensates for a change in color balance due to a change over time during use.

JP-A-2015-106130

In the technique described in Patent Document 1, when the brightness of the light source is set to a specific value, the color change due to the deterioration of the light source is measured, and the retardation plate is rotated accordingly to adjust the color balance. To. However, when the brightness setting of the light source is not limited to a specific single value and there are multiple brightness settings, if the rotation angle of the retardation plate is the same for these multiple brightness settings, the color balance will vary for each brightness setting. There was a problem that it would end up.

On the other hand, the present invention provides a technique for more easily adjusting the color balance for a plurality of brightness settings.

The present invention is a phase difference between a light emitting element that outputs light in the first wavelength band, which is the first polarized state, and a phase difference that converts a part of the light output from the light emitting element according to the rotation angle into the second polarized state. A polarization separation element that separates the light from the plate and the retardation plate into a first light beam in a first polarized state and a second light beam in a second polarized state, and the first wavelength band excited by the first light beam. A phosphor that outputs a third light beam in a second wavelength band different from the above, an optical modulator that modulates the light according to a video signal, and a light emitting element control that controls the brightness of the light emitting element according to brightness information. Provided is a projector having a unit and a retardation plate control unit that controls the rotation angle of the retardation plate according to the brightness information.
According to this projector, the color balance can be adjusted according to the brightness information.

The brightness information may include brightness information set according to a user's instruction input.
According to this projector, the color balance can be adjusted according to the brightness information set according to the input of the user's instruction.

This projector may have a setting unit that sets the brightness information according to the analysis result of the video signal.
According to this projector, the color balance can be adjusted according to the brightness information set according to the analysis result of the video signal.

This projector may have a setting unit that sets the brightness information according to the temperature of the light emitting element.
According to this projector, the color balance can be adjusted according to the brightness information set according to the temperature of the light emitting element.

This projector may have a sensor that detects the illuminance of the light output from the light emitting element, and a setting unit that sets the brightness information according to the output of the sensor.
According to this projector, the color balance can be adjusted according to the brightness information set according to the illuminance of the light output from the light emitting element.

This projector has an integrated unit that integrates a plurality of brightness information, and the retardation plate control unit controls the rotation angle of the retardation plate according to the brightness information integrated by the integrated unit. May be good.
According to this projector, it is possible to adjust the color balance in consideration of a plurality of brightness information.

This projector has a color correction unit that performs color correction according to the brightness information, and the retardation plate control unit controls the rotation angle of the retardation plate according to the correction result of the color correction unit. You may.
According to this projector, the color balance can be adjusted according to the correction result of the color correction unit.

This projector may have a generation unit that generates a table for color correction according to the input / output characteristics of the light emitting element.
According to this projector, the color balance can be adjusted according to the change over time in the input / output characteristics of the light emitting element.

Further, the present invention relates to a step in which the light emitting element outputs light in the first wavelength band in the first polarized state, and a part of the light output from the light emitting element according to the rotation angle of the retardation plate. The step of converting the retardation plate into the second polarization state, the step of separating the light from the retardation plate into the first luminous flux in the first polarization state and the second luminous flux in the second polarization state, and the first luminous flux. The step of outputting the third luminous flux in the second wavelength band different from the first wavelength band, the step of synthesizing the second luminous flux and the third luminous flux, and the step of synthesizing the second luminous flux and the third luminous flux, which were excited by A step of modulating light by an optical modulator according to a video signal, a step of controlling the brightness of the light emitting element according to brightness information, and a step of controlling the rotation angle of the retardation plate according to the brightness information. Provided is a control method having steps to be performed.
According to this projector, the color balance can be adjusted according to the brightness information.

The figure which illustrates the functional structure of the projector 1 which concerns on 1st Embodiment. The figure which illustrates the structure of the optical system 12. The figure which illustrates the structure of the light source 122. The figure which illustrates the functional structure which concerns on 1st Embodiment of a light source control unit 14. A flowchart showing the update process of the color correction table. The figure which illustrates the input / output characteristic of a light source. The figure which illustrates the light source information. The figure which illustrates the relationship between the correction value C and brightness B. Flow chart of rotation angle control process of retardation plate. The figure which illustrates the information shown by the retardation plate table. The figure which illustrates the structure of the light source control unit 14 which concerns on 2nd Embodiment. The figure which illustrates the information shown by the retardation plate table which concerns on 2nd Embodiment. The figure which illustrates the structure of the light source control unit 14 which concerns on 3rd Embodiment. The figure which illustrates the output value of the R sensor used for the analysis of the deterioration state.

1. 1. First Embodiment 1-1. Configuration FIG. 1 is a diagram illustrating the functional configuration of the projector 1 according to the first embodiment. The projector 1 is a projector that automatically adjusts the color balance in each of a plurality of brightness settings.

The projector 1 includes a video signal system 11, an optical system 12, a UI unit 13, a light source control unit 14, a light source information storage unit 15, an optical sensor 16, and a temperature sensor 17. The video signal system 11 controls the light modulator (liquid crystal panel 124 in this example) according to the video signal that has received the input. The video signal system 11 includes a video input unit 111, an image analysis unit 112, an image processing unit 113, a liquid crystal control unit 114, and a liquid crystal drive unit 115. The video input unit 111 receives the input of the video signal. The image analysis unit 112 performs image analysis processing on the video signal. In this example, the image analysis process is, for example, a process of specifying the type of video (movie, sports broadcast, presentation image, etc.) indicated by the video signal. The image processing unit 113 performs predetermined image processing (for example, resizing or keystone correction) on the video signal. The liquid crystal control unit 114 generates a signal for controlling the liquid crystal panel 124 from the video signal. The liquid crystal driving unit 115 outputs a signal for driving the liquid crystal panel 124 in response to the signal output from the liquid crystal control unit 114.

The optical system 12 controls the light projected on the screen SC (hereinafter referred to as “projected light”). The optical system 12 includes a light source driving unit 121, a light source 122, an illumination optical system 123, a liquid crystal panel 124, and a projection optical system 125. The light source driving unit 121 drives the light source 122. The light source 122 outputs illumination light. Illumination light refers to light that is later modulated to become projected light. The illumination light is white light containing a plurality of wavelength band components. The illumination optical system 123 separates the illumination light into a plurality of color components (for example, three colors of red, green, and blue). The light separated into the color components is incident on the individual liquid crystal panels 124. The liquid crystal panel 124 is an example of an optical modulator that modulates the illumination light according to a video signal. The projection optical system 125 synthesizes light modulated for each color component and projects it on the screen SC as projected light.

FIG. 2 is a diagram illustrating a specific configuration of the optical system 12. The illumination optical system 123 includes a dichroic mirror 1231, a dichroic mirror 1232, a reflection mirror 1233, a reflection mirror 1234, a reflection mirror 1235, a relay lens 1236, and a relay lens 1237. In this example, since each of the red light LR, the green light LG, and the blue light LB is individually modulated, the optical system 12 has three liquid crystal panels, a liquid crystal panel 124R, a liquid crystal panel 124G, and a liquid crystal panel 124B. As described above, when the components are distinguished for each color component, the subscripts R, G, and B are used, and when they are not distinguished, the liquid crystal panel 124 is simply described. The same applies to the components other than the liquid crystal panel 124.

The dichroic mirror 1231 separates the illumination light WL output from the light source 122 into red light LR and non-red light (green light LG and blue light LB). The dichroic mirror 1231 transmits the red light LR and reflects the green light LG and the blue light LB. The dichroic mirror 1232 separates the light reflected by the dichroic mirror 1231 into green light LG and blue light LB. The dichroic mirror 1232 reflects the green light LG and transmits the blue light LB.

The reflection mirror 1233 is arranged in the optical path of the red light LR. The reflection mirror 1233 reflects the red light LR transmitted through the dichroic mirror 1231 and guides it to the liquid crystal panel 124R. The reflection mirror 1233 and the reflection mirror 1235 are arranged in the optical path of the blue light LB. The reflection mirror 1233 and the reflection mirror 1235 reflect the blue light LB transmitted through the dichroic mirror 1232 and guide it to the liquid crystal panel 124B. The green light LG is reflected by the dichroic mirror 1232 and guided to the liquid crystal panel 124G.

The relay lens 1236 and the relay lens 1237 are arranged on the output side of the dichroic mirror 1232 in the optical path of the blue light LB. The relay lens 1236 and the relay lens 1237 compensate for the optical loss of the blue light LB caused by the optical path length of the blue light LB being longer than the optical path length of the red light LR and the green light LG.

The liquid crystal panel 124R, the liquid crystal panel 124G, and the liquid crystal panel 124B modulate the red light LR, the green light LG, and the blue light LB according to the video signal, respectively. As the liquid crystal panel 124R, the liquid crystal panel 124G, and the liquid crystal panel 124B, for example, a transmissive liquid crystal panel is used. A field lens 1238 for parallelizing the incident light is provided on the incident side of the liquid crystal panel 124. The light modulated by the liquid crystal panel 124R, the liquid crystal panel 124G, and the liquid crystal panel 124B is synthesized by the cross dichroic prism 1239.

The projection optical system 125 has at least one projection lens, and may further include a mirror and a prism. The projection optical system 125 projects the light synthesized by the cross dichroic prism 1239 onto the screen SC.

In this example, the optical sensor 16 has an R sensor 161 and a B sensor 162. The R sensor 161 is a sensor that measures the illuminance of the red light LR. The B sensor 162 is a sensor that measures the illuminance of the blue light LB. In this example, the R sensor 161 is provided behind the reflection mirror 1233. The back side of the reflection mirror 1233 means the back side of the surface of the reflection mirror 1233 on which the red light LR is incident. The reflection mirror 1233 transmits the red light LR at a predetermined ratio. The R sensor 161 measures this transmitted light. The B sensor 162 is provided behind the reflection mirror 1235. The reflection mirror 1235 transmits blue light LB at a predetermined ratio. The B sensor 162 measures this transmitted light.

FIG. 3 is a diagram illustrating the configuration of the light source 122. Here, the principle of the light source 122 will be described first before the detailed structure. The light source 122 includes an LD (laser diode) array 1221, a retardation plate 1222, a polarization separating element 1223, and a phosphor 1224. The LD array 1221 is an example of a light emitting element that outputs light in a specific wavelength band (for example, light in a wavelength band corresponding to blue with a peak wavelength of 446 nm; hereinafter referred to as “B light”), and in this example, it has an array shape. Includes multiple laser diodes located in. The light output from the LD array 1221 is S-polarized light (an example of the first polarized state). The retardation plate 1222 is an example of a retardation plate that converts a part of the light output from the light emitting element according to the rotation angle into the second polarized state. Specifically, the retardation plate 1222 converts a part of the S-polarized light output from the LD array 1221 into P-polarized light (an example of the second polarized state). The ratio of the light output from the LD array 1221 converted to P-polarized light (that is, the ratio of S-polarized light and P-polarized light) varies depending on the angle of the retardation plate 1222 with respect to the incident light. The angle of the LD array 1221 with respect to the incident light (hereinafter referred to as “rotation angle”) is controlled by the motor 12203. The retardation plate 1222 is referred to as a rotation retardation plate in the sense that the rotation angle is variable by the motor 12203.

The polarization separation element 1223 separates the light output from the retardation plate 1222 into two light fluxes according to the polarization state. The polarization separation element 1223 is an example of a polarization separation element that separates the light from the retardation plate into the first light flux in the first polarization state and the second light flux in the second polarization state. In this example, the polarization separating element 1223 reflects S-polarized light and transmits P-polarized light. The light reflected by the polarization separating element 1223 (an example of the first luminous flux) is incident on the phosphor 1224. The phosphor 1224 is excited by light in the first wavelength band, and is light in a second wavelength band (for example, a wavelength band corresponding to yellow) different from the first wavelength band (an example of a third luminous flux, hereinafter referred to as “Y light”. ) Is output. The B light transmitted through the polarization separating element 1223 (an example of the second luminous flux) is finally combined with the Y light output from the phosphor 1224, and is output to the outside of the light source 122 as white light containing components in multiple wavelength bands. Will be done.

As can be seen from the above description, of the light output from the LD array 1221, the S polarized light is converted into the Y light, the P polarized light remains the B light, and both are finally combined. The fact that the ratio of S-polarized light and P-polarized light changes depending on the rotation angle of the retardation plate 1222 means that the ratio of Y light and B light changes depending on the rotation angle of the retardation plate 1222. That is, in the light source 122, the balance between the Y light and the B light (hereinafter referred to as "color balance") can be adjusted.

Hereinafter, a specific configuration example of the light source 122 will be described. The B light output from the LD array 1221 is incident on the collimator optical system 12201. The collimator optical system 12201 converts the B light output from the LD array 1221 into a parallel luminous flux. The collimator optical system 12201 is composed of, for example, a plurality of collimator lenses arranged side by side in an array. The plurality of collimator lenses are arranged corresponding to the plurality of laser diodes.

The B light output from the collimator optical system 12201 is incident on the afocal optical system 12202. The afocal optical system 12202 adjusts the luminous flux diameter of the B light. In this example, the afocal optical system 12202 is composed of, for example, two afocal lenses.

The B light output from the afocal optical system 12202 is incident on the retardation plate 1222. The retardation plate 1222 is composed of a 1/2 wave plate with respect to B light (wavelength 446 nm in this example). The optical axis of the retardation plate 1222 intersects the polarization axis of the B light incident on the retardation plate 1222. The optical axis of the retardation plate 1222 may be either a phase advance axis or a phase delay axis of the retardation plate 1222. The B light incident on the retardation plate 1222 is coherent S-polarized light. The B light transmitted through the retardation plate 1222 is light in which the S polarization component BLs and the P polarization component BLp are mixed at a predetermined ratio. A motor 12203 for rotating the retardation plate 1222 is connected to the retardation plate 1222. The motor 12203 is, for example, a stepping motor.

The B light output from the retardation plate 1222 is incident on the homogenizer optical system 12204. The homogenizer optical system 12204 converts the light intensity distribution of B light into a uniform light intensity distribution called, for example, a top hat type distribution. In this example, the homogenizer optical system 12204 is composed of two multi-lens arrays.

The B light output from the homogenizer optical system 12204 is incident on the prism 12205. The prism 12205 is composed of, for example, a dichroic prism having wavelength selectivity. The dichroic prism has an inclined surface K forming an angle of 45 ° with respect to the optical axis ax1. The inclined surface K also forms an angle of 45 ° with respect to the optical axis ax2. The prism 12205 is arranged so that the intersection of the optical axes ax1 and the optical axis ax2 orthogonal to each other and the optical center of the inclined surface K coincide with each other. A parallel flat plate dichroic mirror may be used instead of the prism 12205. The optical axis ax1 and the optical axis ax2 are in the same plane and are in a positional relationship orthogonal to each other.

A polarization separating element 1223 having wavelength selectivity is provided on the inclined surface K. The polarization separating element 1223 separates B light into S polarization component BLs and P polarization component BLp. Specifically, the polarization separating element 1223 reflects the S polarization component BLs and transmits the P polarization component BLp. Since the S polarization component BLs reflected by the polarization separation element 1223 is used for exciting the phosphor 1224, they are hereinafter referred to as excitation light BLs. The P polarization component BLp transmitted through the polarization separation element 1223 is simply referred to as B light.

The excitation light BLs output from the polarization separation element 1223 are incident on the pickup optical system 12206. The pickup optical system 12206 concentrates the excitation light BLs on the phosphor 1224 of the fluorescence element 12207. The pickup optical system 12206 is composed of two pickup lenses in this example. The fluorescent element 12207 has a phosphor 1224 and a substrate 12208. The substrate 12208 supports the phosphor 1224. When the excitation light BLs is incident, the phosphor 1224 is excited and the fluorescent light is output. The fluorescent light is light having a wavelength different from that of the excitation light BLs (in this example, it is called Y light because it is light in the yellow wavelength band). The phosphor 1224 is attached to the substrate 12208 by an adhesive 12209 provided between the side surface of the phosphor 1224 and the substrate 12208 in a state where the surface opposite to the side on which the excitation light BLs is incident is in contact with the substrate 12208. It is fixed. A heat sink 12210 for dissipating the heat of the phosphor 1224 is provided on the surface of the substrate 12208 opposite to the side on which the phosphor 1224 is provided.

Since the Y light output from the phosphor 1224 is unpolarized light whose polarization directions are not aligned, it passes through the pickup optical system 12206 and then enters the polarization separation element 1223 in the unpolarized state. The polarization separating element 1223 transmits fluorescent light having a wavelength band different from that of B light regardless of the polarization state of Y light.

On the other hand, the B light output from the polarization separating element 1223 is incident on the retardation plate 12211. The retardation plate 12211 is composed of, for example, a quarter wave plate. The retardation plate 12211 converts the polarized state of B light into circularly polarized light. The B light output from the retardation plate 12211 is incident on the pickup optical system 12212. The pickup optical system 12212 collects B light on the diffuse reflection element 12213. The pickup optical system 12212 is composed of two pickup lenses in this example.

The diffuse reflection element 12213 diffusely reflects B light. As the diffuse reflection element 12213, it is preferable to use one that Lambertian reflects the incident light. By using such a diffuse reflection element, B light having a uniform illuminance distribution can be obtained. The B light diffusely reflected by the diffuse reflection element 12213 is incident on the retardation plate 12211 again, and is converted from circularly polarized light to S-polarized light. The B light output from the retardation plate 12211 is reflected by the polarization separating element 1223.

As a result, the polarization separating element 1223 outputs Y light and B light in the same direction. That is, the polarization separating element 1223 also functions as a synthetic element that synthesizes Y light and B light. The light output from the polarization separating element 1223 is called illumination light.

The illumination light output from the polarization separating element 1223 is incident on the integrator optical system 12214. The integrator optical system 12214 divides the illumination light WL into a plurality of small luminous fluxes. The integrator optical system 12214 is composed of two lens arrays in this example. The lens array is an array of a plurality of microlenses.

The illumination light output from the integrator optical system 12214 is incident on the polarization conversion element 12215. The polarization conversion element 12215 aligns the polarization directions of the illumination light WL. The polarization conversion element 12215 is composed of, for example, a polarization separation membrane, a retardation plate, and a mirror. The polarization conversion element 12215 converts one polarization component into the other polarization component, for example, the P polarization component into an S polarization component, in order to align the polarization direction of the unpolarized Y light and the polarization direction of the S-polarized B light. To do. The superimposing lens 12216 superimposes a plurality of small luminous fluxes emitted from the polarization conversion element 12215 on the object to be illuminated.

See FIG. 1 again. The UI unit 13 receives an input of an instruction from the user. Here, in particular, an input of an instruction for setting the brightness of the light source 122 is accepted. The UI unit 13 outputs the brightness information set in response to the user's instruction input. The optical sensor 16 measures the illuminance of the separated light in the optical system 12 (particularly the illumination optical system 123). The temperature sensor 17 is a sensor for measuring the temperature of the light source 122, and is provided in the vicinity of the light source 122. The light source information storage unit 15 stores information regarding the input / output characteristics of the light source 122 (hereinafter referred to as “light source information”).

The light source control unit 14 controls the light source 122 (via the light source drive unit 121). More specifically, the light source control unit 14 controls the color balance of the light source 122. The color balance is controlled based on the brightness information. The brightness information refers to information for setting the brightness of the light output from the light source 122, and refers to information that directly or indirectly indicates the brightness of the light output from the light source 122. In this example, the brightness information is provided independently from the image analysis unit 112, the UI unit 13, and the temperature sensor 17. Although the details will be described later, the light source control unit 14 controls the color balance of the light source 122 by using the information that integrates the plurality of brightness information. When distinguishing the brightness information before and after the integration, the brightness information before the integration is called "individual brightness information", and the brightness information after the integration is called "integrated brightness information". The "individual brightness information" includes information supplied from the image analysis unit 112 (referred to as "brightness information (video)"), information supplied from the UI unit 13 (referred to as "brightness information (UI)"), and the like. And what is supplied from the temperature sensor 17 (referred to as "brightness information (temperature)"). When individual brightness information and integrated brightness information are not distinguished, they are simply referred to as brightness information.

FIG. 4 is a diagram illustrating a functional configuration according to the first embodiment of the light source control unit 14. The light source control unit 14 includes an integration unit 141, a light source calibration unit 142, a light source information storage unit 15, a table generation unit 144, a color correction unit 145, a rotation angle adjustment unit 146, a duty value adjustment unit 147, and a current value adjustment unit 148. Have.

The integration unit 141 integrates a plurality of individual brightness information to generate integrated brightness information. The information output from the image analysis unit 112 is, for example, information indicating the type of video, but the integration unit 141 converts the information indicating the type of video into brightness information according to a predetermined rule (for example,). 80% for movies, 90% for sports broadcasts, 100% for presentation images). Further, the information output from the temperature sensor 17 is information indicating the temperature of the light source 122 (hereinafter referred to as "temperature information"), but the integration unit 141 converts the temperature information into brightness information according to a predetermined rule. Convert. That is, the integration unit 141 functions as a setting unit that sets brightness information based on the output of the image analysis unit 112 or the temperature sensor 17. Further, as will be described later, since the light source information stored in the light source information storage unit 15 is obtained based on the output value of the optical sensor 16, the integrated unit 141 is based on the output of the optical sensor 16. It functions as a setting unit for setting brightness information. The integrated brightness information is used in the color correction unit 145, the duty value adjustment unit 147, and the current value adjustment unit 148.

The color correction unit 145 performs color correction, that is, color balance adjustment based on the integrated brightness information. The color correction unit 145 stores a table (color correction table) in which brightness and color balance correction values are associated with each other. When the integrated brightness information is input, the color correction unit 145 refers to this table and outputs a correction value corresponding to the input integrated brightness information.

The rotation angle adjusting unit 146 converts the color balance correction value into the rotation angle of the retardation plate 1222. The rotation angle adjusting unit 146 stores a table (phase difference plate table) in which the correction value of the color balance and the rotation angle of the retardation plate 1222 are associated with each other. In this example, since the retardation plate 1222 is rotated by the motor 12203 which is a stepping motor, the step value of the motor is stored as information corresponding to the rotation angle of the retardation plate 1222. When the color balance correction value is input, the rotation angle adjusting unit 146 outputs a step value corresponding to the input correction value. This step value is input to the motor driver 1211 of the light source driving unit 121. The motor driver 1211 drives the motor 12203 according to the signal supplied from the rotation angle adjusting unit 146. The motor driver 1211 is an example of a retardation plate control unit that controls the rotation angle of the retardation plate 1222 according to the brightness information.

The duty value adjusting unit 147 adjusts the duty value based on the integrated brightness information. The duty value means a duty value (duty ratio) in PWM (Pulse Width Modulation) control. The duty value adjusting unit 147 stores a table (duty value table) in which the brightness and the duty value are associated with each other. When the integrated brightness information is input, the duty value adjusting unit 147 refers to this table and outputs the duty value corresponding to the input integrated brightness information.

The current value adjusting unit 148 adjusts the current value based on the integrated brightness information. The current value adjusting unit 148 stores a table (current value table) in which the brightness and the current value are associated with each other. When the integrated brightness information is input, the current value adjusting unit 148 refers to this table and outputs the current value corresponding to the input integrated brightness information. The duty value and the current value are input to the LD driver 12112 of the light source driving unit 121. The LD driver 1212 drives the LD array 1221 according to the signals supplied from the duty value adjusting unit 147 and the current value adjusting unit 148. The LD driver 1212 is an example of a light emitting element control unit that controls the brightness of the LD array 1221 according to the brightness information.

The light source calibration unit 142 acquires information regarding the input / output characteristics of the light source 122 (hereinafter referred to as “light source information”). The input / output characteristic indicates how the brightness of the illumination light output from the light source 122 changes with respect to the supplied current value. The light source calibration unit 142 acquires light source information from the output signals of the light sensor 16 and the temperature sensor 17. The light source calibration unit 142 stores the acquired light source information in the light source information storage unit 15. The table generation unit 144 updates the table stored in the color correction unit 145, the duty value adjustment unit 147, and the current value adjustment unit 148 by using the light source information stored in the light source information storage unit 15. Change).

Of the configurations of FIGS. 1 and 4, the functions of the UI unit 13, the light source control unit 14, and the image analysis unit 112 are implemented in, for example, a CPU (Central Processing Unit). Alternatively, these features may be implemented in a dedicated processor. Further, the function of the light source information storage unit 15 is implemented in a rewritable non-volatile memory (for example, a flash memory).

1-2. Operation 1-2-1. Updating the color correction table FIG. 5 is a flowchart showing an update process of the color correction table. The color correction table update process is started at a predetermined timing, for example, when the power is turned off after the elapsed time since the last time the color correction table was updated exceeds the threshold value. Alternatively, the update process of the color correction table may be started according to the instruction of the user.

In step S11, the light source calibration unit 142 acquires the input / output characteristics of the light source. The input / output characteristic of the light source is, for example, information indicating a change in the output value of the optical sensor 16 with respect to the current value supplied to the LD array 1221. The current supplied to the LD array 1221 is referred to as "drive current", and the value of the drive current is referred to as "drive current value". The light source calibration unit 142 controls the light source drive unit 121 to sequentially change the drive current value. The light source calibration unit 142 records the sensor output value from the optical sensor 16 at each drive current value.

FIG. 6 is a diagram illustrating the input / output characteristics of the light source. In this figure, the horizontal axis represents the drive current value and the vertical axis represents the sensor output value. The sensor output value is represented by a relative value standardized by a reference value. As the reference value, for example, the maximum value of the sensor output value (sensor output value at the maximum drive current) in the newly measured input / output characteristics is used. The reference value (that is, the reference value of the color balance) of the ratio of the maximum output value (absolute value, not the relative value) of the R sensor 161 and the B sensor 162 is stored in the light source information storage unit 15, and the R sensor 161 And one of the sensor output values of the B sensor 162 is further standardized according to this reference value. For example
R sensor maximum output value = 5.0
B sensor maximum output value = 3.6
R sensor maximum output value: B sensor maximum output value = 5: 4
In that situation,
R sensor maximum output value = 100%
B sensor maximum output value = 90%
Is standardized to. As the reference value of the color balance, for example, an initial value measured at the time of shipment from the factory or a design value determined by design is used. Alternatively, a value obtained by multiplying this initial value or design value by a coefficient corresponding to the color mode may be used as a reference value for color balance. The color mode is one of the parameters for setting the color balance in the projector 1. For example, color modes are distinguished according to the viewing environment (whether the room is bright or dark) or the type of video (movie or TV program), and a suitable color balance is preset for each color mode.

In FIG. 6, the output value Sr indicates the output value of the R sensor 161 and the output value Sb indicates the output value of the B sensor 162. In the example of this figure, the plot in the graph is the measurement point and the straight line shows the regression line. Even if the same drive current is supplied to the LD array 1221, the illuminance of the output light is not the same, but changes due to temperature and deterioration of the element due to use. Specifically, the illuminance after aging changes as the current decreases due to an increase in the threshold current (lower limit value of the current that can be oscillated by the laser) due to deterioration. On the other hand, the phosphor 1224 has a characteristic that the conversion efficiency changes depending on the intensity of the excitation light, for example, the conversion efficiency increases as the brightness of the excitation light decreases. Therefore, when the illuminance of the laser light output when the drive current in the LD array 1221 is supplied becomes small, the Y light tends to be relatively stronger than the B light. Further, even if the excitation light having the same illuminance is incident on the phosphor 1224, the illuminance of the output fluorescent light may change due to the temperature and deterioration of the element due to use.

See FIG. 5 again. In step S12, the light source calibration unit 142 converts the sensor output value into brightness. The conversion from the sensor output value to the brightness is performed, for example, by inputting both the output value of the R sensor 161 and the output value of the B sensor 162 into a predetermined relational expression. Alternatively, the output value of the R sensor 161 may be simply read as brightness. Further, the brightness may be a value obtained by performing a predetermined correction process on the output value of the R sensor 161. The R sensor 161 indirectly measures the illuminance of the Y light, because the Y light has a greater contribution to the brightness than the B light in human vision.

In step S13, the light source calibration unit 142 writes the light source information in the light source information storage unit 15. The light source information written here is information indicating a change in brightness with respect to the drive current value. By updating the light source information as needed in this way, it is possible to perform correction according to the input / output characteristics of the LD array 1221 at that time.

FIG. 7 is a diagram illustrating light source information. In this example, the output value of the R sensor 161 is used as the brightness, and the shape of the graph is the same as that of the output value Sr in FIG. The light source information to be written may be a set of coordinates of points corresponding to measurement points, or information for specifying a regression line (for example, slope and intercept). Further, an approximate curve other than the regression line may be used.

See FIG. 5 again. When the control signal instructs the generation of the color correction table, the table generation unit 144 generates (updates) the color correction table (step S14). The details are as follows. The table generation unit 144 calculates the color balance correction value C according to the following equation (1) using the information stored in the light source information storage unit 15.
C (B) = Rs (B) / Rm (B) ... (1)
(Rm (B) = Sb (B) / Sr (B))
C (B) is the correction value when the brightness is B, Rs (B) is the target value of the color balance when the brightness is B, and Rm (B) is the actual measurement when the brightness is B. Sb (B) shows the output value of the B sensor 162 when the brightness is B, and Sr (B) shows the output value of the R sensor 161 when the brightness is B. .. As is clear from this definition, the correction value C becomes smaller as the illuminance of the B light with respect to the Y light becomes higher. By calculating the correction value C from the equation (1) for the plurality of brightness Bs, the relationship between the correction value C and the brightness B can be obtained.

FIG. 8 is a diagram illustrating the relationship between the correction value C and the brightness B. In this figure, the horizontal axis represents the brightness and the vertical axis represents the color balance correction value C. The table generation unit 144 updates the color correction table by writing data that tabulates the relationship between the correction value C and the brightness B to the color correction unit 145.

According to this embodiment, the color correction table is updated at any time according to the state of the light source 122 (specifically, the LD array 1221 and the phosphor 1224). Although detailed description is omitted, the table generation unit 144 also updates the duty value table and the current value table based on the light source information in the same manner.

1-2-2. Rotation angle control of the retardation plate FIG. 9 is a flowchart of the rotation angle control process of the retardation plate. The rotation angle control process of the retardation plate is executed at a predetermined timing, for example, every time the individual brightness information is updated, or every frame of the image indicated by the image signal. Alternatively, the rotation angle control process of the retardation plate may be started by a user's instruction.

In step S21, the integration unit 141 acquires individual brightness information. In this example, the integration unit 141 acquires brightness information (video), brightness information (UI), and brightness information (temperature).

In step S22, the integration unit 141 integrates a plurality of individual brightness information to generate integrated brightness information. In this example, the brightness information (video), the brightness information (UI), and the brightness information (temperature) are all expressed as percentages, and by multiplying these three brightness information, the integrated brightness is achieved. Information is generated. The method of obtaining the integrated brightness information from the individual brightness information is not limited to this. For example, the integrated brightness information is generated by weighted multiplication or weighted addition of the individual brightness information. May be good.

When the integrated brightness information is input from the integrated unit 141, the color correction unit 145 performs color correction (step S23). Specifically, the color correction unit 145 refers to the stored color correction table (FIG. 8) and outputs the correction value C corresponding to the input integrated brightness information. When the correction value C is input from the color correction unit 145, the rotation angle adjustment unit 146 determines the rotation angle (step S24).

FIG. 10 is a diagram illustrating the information shown by the retardation plate table. In this figure, the horizontal axis represents the correction value C, and the vertical axis represents the step value of the motor 12203. The rotation angle adjusting unit 146 refers to the retardation plate table and reads out the step value corresponding to the correction value C. The rotation angle adjusting unit 146 outputs this step value to the motor driver 1211. When the step value is input, the motor driver 1211 controls the motor 12203 according to the input step value. That is, the rotation angle of the retardation plate 1222 is adjusted to a desired value (step S25).

To adjust the color balance according to the brightness setting, for example, prepare a phase difference plate table for each brightness setting in advance, and refer to the corresponding phase difference plate table according to the brightness setting for the phase difference. It is also conceivable to adjust the rotation angle of the plate 1222. However, this method is complicated because the projector 1 needs to hold a large amount of data. According to this embodiment, the color balance can be adjusted according to the brightness information. That is, the color balance can be adjusted according to each of the plurality of brightness settings. Further, in the present embodiment, since the color balance is adjusted according to the light source information that changes at any time of the light source 122, it is possible to cope with the time-dependent change of the light source 122.

When the integrated brightness information is input from the integrated unit 141, the duty value adjusting unit 147 adjusts the duty value (step S26). The duty value adjusting unit 147 stores a table (hereinafter, referred to as “duty value table”) in which the brightness of the light source 122 and the duty value are associated with each other (not shown). The duty value adjusting unit 147 refers to this duty value table and reads out the duty value corresponding to the integrated brightness information. The duty value adjusting unit 147 outputs this duty value to the LD driver 1212.

When the integrated brightness information is input from the integrated unit 141, the current value adjusting unit 148 adjusts the drive current value (step S27). The current value adjusting unit 148 stores a table (hereinafter, referred to as “current value table”) in which the brightness of the light source 122 and the driving current value are associated with each other (not shown). The current value adjusting unit 148 refers to this current value table and reads out the current value corresponding to the integrated brightness information. The current value adjusting unit 148 outputs this current value to the LD driver 1212.

The LD driver 1212 drives the LD array 1221 according to the input duty value and current value (step S28). That is, the illuminance of the light output from the LD array 1221 is adjusted.

2. 2. The second embodiment FIG. 11 is a diagram illustrating the configuration of the light source control unit 14 according to the second embodiment. Hereinafter, the differences from the light source control unit 14 in the first embodiment will be mainly described. In this example, the configuration related to color correction in the light source control unit 14 according to the first embodiment is deleted. The light source control unit 14 according to the second embodiment is suitable when it is not necessary to consider the deterioration with time of the light source 122 or when the deterioration with time is negligibly small.

In this example, the rotation angle adjusting unit 146 converts the integrated brightness information into the rotation angle of the retardation plate 1222. The rotation angle adjusting unit 146 stores a table (a retardation plate table according to the second embodiment) in which the brightness and the rotation angle of the retardation plate 1222 are associated with each other.

FIG. 12 is a diagram illustrating information shown by the retardation plate table according to the second embodiment. In this figure, the horizontal axis represents the brightness B, and the vertical axis represents the step value of the motor 12203. The rotation angle adjusting unit 146 refers to the retardation plate table and reads out the step value corresponding to the brightness B. The rotation angle adjusting unit 146 outputs this step value to the motor driver 1211. When the step value is input, the motor driver 1211 controls the motor 12203 according to the input step value.

According to the present embodiment, the rotation angle of the retardation plate 1222 is controlled according to the brightness information with a simpler configuration. That is, the color balance can be adjusted according to the brightness information. In this example, the light source information storage unit 15, the optical sensor 16, and the temperature sensor 17 are unnecessary.

3. 3. Third Embodiment FIG. 13 is a diagram illustrating the configuration of the light source control unit 14 according to the third embodiment. Hereinafter, the differences from the light source control unit 14 in the first embodiment will be mainly described. The light source control unit 14 according to the third embodiment includes a deterioration analysis unit 241 and an integration unit 242 in addition to the configuration of the light source control unit 14 according to the first embodiment.

The deterioration analysis unit 241 analyzes the deterioration state of the light source 122. In this example, the deterioration analysis unit 241 analyzes the deterioration state from the light source information, more specifically, from the output value of the R sensor 161 at a predetermined drive current value.

FIG. 14 is a diagram illustrating an output value of the R sensor 161 used for analysis of the deterioration state. In this figure, the output value Sr_O represents a reference value of the output value. As the reference value, for example, a sensor output value or a design value measured at the time of shipment from the factory is used. The deterioration analysis unit 241 or the light source information storage unit 15 stores a reference value of an output value. In this example, the sensor output value is measured at two points, a relatively low drive current value I1 and a high drive current value I2. The deterioration analysis unit 241 calculates a deterioration coefficient β indicating a deterioration state of the light source 122 from these sensor output values. The deterioration coefficient β is calculated according to, for example, the following equation (2).
β = {Sr (I1) / Sr_O (I1) + Sr (I2) / Sr_O (I2)} / 2
… (2)
The method for calculating the deterioration coefficient β is not limited to the equation (2). For example, the deterioration coefficient β may be calculated using the sensor output value at a specific driving current value at one point.

The integration unit 242 integrates the integrated brightness information output from the integration unit 141 and the deterioration coefficient output from the deterioration analysis unit 241. Specifically, the integration unit 242 multiplies the integrated brightness information and the deterioration coefficient β. By multiplying the deterioration coefficient β, the integrated brightness information corresponds to the brightness information in consideration of the deterioration of the light source 122 in addition to the brightness setting. The integration unit 242 outputs the integrated brightness information multiplied by the deterioration coefficient β to the color correction unit 145. The color correction unit 145 performs color correction based on the brightness information input from the integration unit 242.

According to this embodiment, the color balance can be adjusted in consideration of the change (deterioration) of the light source 122 from the reference state. In this example, the B sensor 162 is unnecessary.

4. Modifications The present invention is not limited to the above-described embodiment, and various modifications can be performed. Hereinafter, some modification examples will be described. Two or more of the following modifications may be used in combination.

The brightness information considered is not limited to that illustrated in the embodiments. For example, at least one of brightness information (video), brightness information (UI), and brightness information (temperature) may be omitted. Alternatively, brightness information other than these three may be used.

The brightness information (temperature) is not limited to that obtained from the output value of the temperature sensor 17. Any information may be used as long as it is information on the temperature of the light source 122. For example, since the temperature of the light source 122 is considered to be low immediately after the projector 1 is started, the elapsed time after the power of the projector 1 is turned on may be used as the brightness information (temperature). In this case, the temperature sensor 17 is unnecessary.

The light source control unit 14 may use a single individual brightness information as it is for color correction or the like without integrating a plurality of individual brightness information. In this case, the function of integrating the individual brightness information to generate the integrated brightness information is unnecessary.

The arrangement of the R sensor 161 and the B sensor 162 is not limited to that illustrated in FIG. For example, an optical member that branches light may be arranged on the optical path of the red light LR, and the R sensor 161 may be arranged at a position where the branched light is incident. The same applies to the B sensor 162.

The specific hardware configuration of the projector 1 is not limited to that illustrated in the embodiment. For example, as the light modulator, a reflective liquid crystal panel or a DMD (Digital Miller Device) may be used instead of the transmissive liquid crystal panel.

The wavelength and polarization state of light used in the light source 122 are merely examples, and the present invention is not limited thereto.

1 ... Projector, 11 ... Video signal system, 12 ... Optical system, 13 ... UI unit, 14 ... Light source control unit, 15 ... Light source information storage unit, 16 ... Optical sensor, 17 ... Temperature sensor, 141 ... Integrated unit, 142 ... Light source calibration unit, 144 ... Table generation unit, 145 ... Color correction unit, 146 ... Rotation angle adjustment unit, 147 ... Duty value adjustment unit, 148 ... Current value adjustment unit, 161 ... R sensor, 162 ... B sensor, 241 ... Deterioration Analysis unit, 242 ... Integration unit

Claims (8)

A light emitting element that outputs light in the first wavelength band, which is the first polarized state,
A retardation plate that converts a part of the light output from the light emitting element according to the rotation angle into the second polarized state, and
A polarizing separation element that separates the light from the retardation plate into a first luminous flux in the first polarized state and a second luminous flux in the second polarized state.
A phosphor that is excited by the first luminous flux and outputs a third luminous flux in a second wavelength band different from the first wavelength band.
A synthetic element that synthesizes the second luminous flux and the third luminous flux, and
An optical modulator that modulates the light output from the synthesis element according to the video signal, and
A light emitting element control unit that controls the brightness of the light emitting element according to the brightness information,
A retardation plate control unit that controls the rotation angle of the retardation plate according to the brightness information,
A deterioration analysis unit that analyzes the deterioration state of the light source and outputs the deterioration coefficient,
An integrated unit that integrates the brightness information and the deterioration coefficient and outputs integrated brightness information,
Have a color correction unit for performing color correction on the basis of the integrated brightness information,
The brightness information includes brightness information set according to a user's instruction input, brightness information set according to the analysis result of the video signal, and brightness set according to the temperature of the light emitting element. A projector that contains at least one piece of information . The projector according to claim 1, further comprising a setting unit for setting the brightness information according to the analysis result of the video signal. The projector according to claim 1 or 2 , further comprising a setting unit that sets the brightness information according to the temperature of the light emitting element. A sensor that detects the illuminance of the light output from the light emitting element,
The projector according to any one of claims 1 to 3 , further comprising a setting unit that sets the brightness information according to the output of the sensor. It has an integrated part that integrates multiple brightness information.
The projector according to claim 1, wherein the retardation plate control unit controls the rotation angle of the retardation plate according to the brightness information integrated by the integration unit. It has a color correction unit that performs color correction according to the brightness information.
The projector according to any one of claims 1 to 5 , wherein the retardation plate control unit controls the rotation angle of the retardation plate according to a correction result of the color correction unit. The projector according to claim 6 , further comprising a generator that generates a table for color correction according to the input / output characteristics of the light emitting element. A step in which the light emitting element outputs light in the first wavelength band, which is the first polarized state,
A step of converting a part of the light output from the light emitting element according to the rotation angle of the retardation plate into the second polarization state by the retardation plate.
A step of separating the light from the retardation plate into a first luminous flux in the first polarized state and a second luminous flux in the second polarized state.
A step in which the phosphor outputs a third luminous flux in a second wavelength band different from the first wavelength band, which is excited by the first luminous flux.
A step in which the synthesizing element synthesizes the second luminous flux and the third luminous flux,
A step in which the light modulator modulates the light output from the synthesis element according to the video signal.
A step of controlling the brightness of the light emitting element according to the brightness information,
A step of controlling the rotation angle of the retardation plate according to the brightness information,
The step of analyzing the deterioration state of the light source and outputting the deterioration coefficient,
A step of integrating the brightness information and the deterioration coefficient and outputting the integrated brightness information,
Possess and performing color correction on the basis of the integrated brightness information,
The brightness information includes brightness information set according to a user's instruction input, brightness information set according to the analysis result of the video signal, and brightness set according to the temperature of the light emitting element. A control method that includes at least one piece of information .

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